1. Field
This invention is in the field of athletic shoes which provide a cushioning effect on the feet during motions such as walking, jumping, and running.
2. State of the Art
Shoes with cushioned soles are well known in the art. The majority of these, however, rely on a cushioned sole made of a foam-type material. The problems associated with a sole comprising such a material are twofold. First, the sole loses its cushioning abilities and wears out after a relatively short time. This creates the added expense and inconvenience of replacing either the individual sole or the entire shoe at a more frequent rate than is desirable. Second, cushioned soles made of foam-type material do not always provide adequate support for the arch, ball, heel and other critical areas of the foot. Such lack of support can cause innumerable foot and leg injuries like shin splints, bone spurs, and muscle spasms and tears.
Other systems for cushioning the foot are becoming quite common. For example, at least one shoe manufacturer produces a shoe which has inflatable chambers actuated by a push-button pump. These chambers are inflated in anticipation of strenuous activity and deflated after completion thereof. Theoretically, the chambers are filled only to the level which will provide the proper amount of support for the intended activity and thus provide the advantage of variable support. Some problems, however, have been associated with this system as well. Inadvertent leakage of the pumped air has required an increase in the wall thickness of the chambers, resulting in a decreased level of responsiveness in the chambers' performance. Furthermore, the pumps are easily broken, which negates any advantage the system may have provided in the first place.
Another system calls for the provision of gel or compressed air to be placed in closed pockets in the sole of the shoe, which has disadvantages.
Other known systems have various features in common with the present invention, e.g. the systems of Fowler U.S. Pat. No. 3,834,046 of Sep. 10, 1974, and of LICO Sportschuhfabriken, German DE 3507295 A1 of Sep. 4, 1986, but lack the combination of features that have made the present invention operatively superior.